Preform design of blade forging has been optimized by utilizing developed topology method in this study. The key techniques of 3D topology optimization include optimization strategy, optimization objectives, element addition and removal criterion, geometry model treatment are given in detail. To fulfill the objective of increased raw material utilizing rate and die-filling rate, a theoretical optimized preform has been obtained after a dozen optimization iterations based on the self-programmed code. Blade forging experiments are implemented to validate the formability of optimized preform form. Aerofoil section profiles extracted from actual forged blade by utilizing laser measure equipment are compared with that from the FE results. The preparation technology of optimized preform is also discussed. A satisfactory optimal result of preform design has been achieved by utilizing the topological method.